/Engine/Source/Runtime/Engine/Public/SkeletalMeshMerge.h
Creates the merged mesh from the 'SrcMeshList' (note, this should only be called afterMergeSkeleton()). Use when the reference skeleton is needed prior to finalizing the merged meshes (do not use withDoMerge()).
'true' if successful; 'false' otherwise.
bool FinalizeMesh()